Edge percentage is a way of expressing how much of an advantage your probability estimate gives you over the price in the market. A positive edge means you believe the outcome is more likely than the bookmaker is giving credit for. A negative edge means you are paying for probability the bookmaker has already priced in.
It is closely related to expected value: edge % expresses the gap as a percentage of the implied probability, making it easier to compare opportunities across different odds and markets.
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The formula
Edge % = (Your probability − Implied probability) ÷ Implied probability × 100
Example: You assess a home win at 55% probability. The bookmaker's odds imply 48%.
Edge % = (0.55 − 0.48) ÷ 0.48 × 100 = 14.6%
This means your assessed probability is 14.6% higher than what the bookmaker is pricing. In betting terms, that is a meaningful edge.
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What the numbers mean in practice
There are no hard rules, but some rough guides:
- Below 5%: the edge is small and the error margin in your probability estimate may be larger than the edge itself. Proceed with caution.
- 5-10%: a reasonable edge for a well-researched bet, assuming your probability estimate is solid.
- Above 10%: a strong signal that the market may be mispricing the outcome, assuming you trust your probability source.
The accuracy of your probability estimate is everything. A 12% edge based on a robust model is meaningful. A 12% edge based on a gut feel is essentially meaningless.
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Why edge % is more useful than just odds comparison
Bettors often look for "high odds" as a proxy for value. A 5.00 shot feels more interesting than a 1.70 favourite. But high odds are not the same as edge.
A 5.00 shot (20% implied probability) where your assessed probability is 21% is a 5% edge, interesting but modest. A 1.70 shot (59% implied probability) where your assessed probability is 68% is a 15% edge, more significant despite the lower odds.
Edge % cuts through the distraction of the headline price and focuses on the actual gap between your view and the market's view.
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How BetSignals uses edge
BetSignals rates each signal based on model probability and cross-model agreement. A ★★★ rating means both independent models agree on the outcome direction and the primary model gives that outcome greater than 50% probability. The expected value is a separate calculation comparing the model's fair price against the best available market price. A high star rating and positive EV are independent signals; when both appear together, it means the model has strong conviction on the outcome and the market is pricing it generously confidence level.
When you see a ★★★ signal rating alongside positive EV on a market, the model has identified both strong probability alignment and a meaningful gap between its probability estimate and the bookmaker's implied probability.
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Edge % and your betting process
Edge % is most useful as a filter and a discipline tool. Some practical applications:
Setting a minimum threshold. Decide in advance that you will only act on bets where the edge exceeds, say, 7%. This removes the temptation to back marginally priced outcomes just because you think they will happen.
Comparing two opportunities. If you have two selections and limited bankroll, edge % gives you a rational way to decide which to prioritise.
Keeping records. Track the edge % you bet at alongside outcomes. Over time, this tells you whether your probability estimates are accurate: if your 10% edge bets are actually losing, your probability estimates might be inflated. See the record keeping guide.
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The limits of edge %
Edge % assumes your probability estimate is correct. If your assessment is off by 10 percentage points in the wrong direction, a calculated 12% edge is actually a negative one.
This is why the source of your probability matters as much as the calculation itself. A model-generated probability with a known track record of accuracy is a better input than an intuition dressed up as a number.
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Next reads
- Expected Value in Football Betting: EV and edge %, explained together
- Implied Probability Explained: how to get the bookmaker's implied probability from decimal or fractional odds
- How to Keep Betting Records: tracking edge % over time to validate your approach
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